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Plant Physiology
by Lincoln Taiz and Eduardo Zeiger
WHAT IS PHYSIOLOGY?
Physiology focus on:
How organisms, organ systems, organs, cells,
and bio-molecules carry out the chemical or
physical functions that exist in a living system
PLANT PHYSIOLOGY
Closely related fields include:
1. plant morphology (structure of plants),
2. plant ecology (interactions with the
environment)
3. phytochemistry (biochemistry of plants),
4. cell biology,
5. genetics,
6. biophysics
7. molecular biology.
What kind of unique bioprocesses
do plants have?
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Photosynthesis,
Respiration,
Plant nutrition,
Plant hormone functions,
Tropisms, (in latin, tropos, a turning)
Nastic movements, movements are non-directional responses to
stimuli (e.g. temperature, light irradiance),
• Photoperiodism,
physiological reaction of organisms to the length of
day or night
• Photomorphogenesis,
What kind of unique bioprocesses
do plants have?
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Circadian rhythms,
Environmental stress physiology,
Seed germination,
Dormancy and stomata function and
transpiration,
Dormancy is a period in an organism's life cycle when growth,
development, and (in animals) physical activity are temporarily stopped
• Plant water relations
Plants range in size from less than 1 cm
tall to greater than 100 m
duckweed (Lemna)
1 cm tall
Giant Saguaro Cactus
20 meters
Located in
Arizona, California, Sonoran Desert
Surprise Saguaros, besaball team
Edible fruits
spines are sometimes used as sewing needles
Redwood Tree
Servi ağacı
http://www.youtube.com/watch?v=C9LHjV48e9s
Helios - 114,58 meter
Location: Redwood Creek ,
California, ABD
Modern Plant Physiology:
A highly interdisciplinary field
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Physiology
Biochemistry
Genetics
Molecular Biology
Biotechnology
Structural Biology
Developmental Biology
What is Plant?
Why Study Plants?
B. Fibers-1. Cotton:
2. Paper: Average paper
3. Fibers such as nylon and
rayon are processed from
wood fibers.
Why Study Plants?
III. Other molecules
A. Medicines
Taxol from the bark of the
pacific yew tree (Taxus bacata)
is one of the most promising
anti-cancer drugs.
Foxglove (Digitalis lanata)
produces digitoxin, which
treats heart disease
(congestive heart failure).
Rosy periwinkle from
Madagascar treats two
cancers: juvenile leukemia
and Hodgkin’s disease.
Threatened by increasing
population.
Also noteworthy are aspirin, ephedra (banned),
quinine, ginkgolides, and others.
Why Study Plants?
B. Spices
C. Oils
D. Essential amino acids--There are 8 amino acids that we
need in our cells, but we don’t have the ability to produce
them ourselves.
We can most easily get them
from plants. To get the complete
set of essential amino acids,
a combination of
legumes and cereals is best.
E. Fossil fuels like coal, crude oil,
and natural gas are the products of
plants that died a long time ago.
Some “hot” areas in plant and nutrient
research
• Improving plant water-use efficiency
• Improving salt tolerance
• Improving nutritional value of plants (e.g.,
golden rice, increasing Fe content)
• Phytoremediation
An Overview
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Plant Structure
Bryophytes
Small (rarely more than 4 cm in height), very simple
land plants, and the least abundant in terms of number of
species and overall population.
Bryophytes include mosses,
These small plants have life cycles that depend on water during the
sexual phase.
Water facilitates fertilization, the fusion of gametes to produce a
diploid zygote,
Bryophytes are like algae in other respects as well: They have
neither true roots nor true leaves, they lack a vascular system,
and they produce no hard tissues for structural support. The
absence of these structures that are important for growth on
land greatly restricts the potential size of bryophytes,
which, unlike algae, are terrestrial rather than aquatic.
Marchantia, a liverwort, koyun otu
Mosses, karayosunu
Hornworts (boynuz otu) are the third group of bryophytes
Ferns
Represent the largest group of spore-bearing
vascular plants. In contrast to the bryophytes,
ferns have true roots, leaves, and vascular tissues, and
they produce hard tissues for support. These
architectural features enable ferns to grow to the size of
small trees. Although ferns are better adapted to the
drying conditions of terrestrial life than
bryophytes are,
They still depend on water as a medium for
reproduction.
This dependence on water during a critical
stage of their life cycle restricts the
ecological range of ferns to relatively
moist habitats.
The Seed Plants
• Seed plants have been able to adapt to an extraordinary
range of habitats. The embryo, protected and nourished
inside the seed, is able to survive in a dormant state during
unfavorable growing conditions such as drought. Seed
dispersal also facilitates the dissemination of the embryos
away from the parent plant.
• Another important feature of seed plants is their mode of
fertilization. Fertilization in seed plants is brought about by
wind- or insect-mediated transfer of pollen, the gameteproducing structure of the male, the stamen,
The Seed Plants
The most successful terrestrial plants.
Seed Plants need to produce seeds:
WHY they need to do it?
The Seed Plants
There are two categories of seed plants:
Gymnosperms (from the Greek for "naked seed")
Angiosperms (based on the Greek for "vessel seed," or seeds contained in a
vessel).
• Gymnosperms; About 700 species are known. The largest group of
gymnosperms is the conifers ("cone-bearers"), which include such
commercially important forest trees as pine, fir, spruce, and redwood.
• Two types of cones are present:
male cones, which produce pollen,
female cones, which bear ovules.
The ovules are located on the surfaces of specialized
structures called cone scales..
CYCAD-Ceratozamia mexicana
New Jersey’s native Pitch Pine, for example, will remain closed
on the tree for years until exposed to temperatures over
130oF. The strategy here is that the tree will not release seeds
until after a forest fire has burned the twig and leaf debris
from the forest floor, making the site suitable for seedling
germination and growth.
• Angiosperms (based on the Greek for "vessel seed," or
seeds contained in a vessel).
Angiosperms;
Today, they dominate the landscape and about 250,000 species are
known, but many more remain to be characterized.
The major innovation of the angiosperms is the flower; hence they
are referred to as flowering plants.
Angiosperms are divided into two major groups,
• Dicotyledons (dicots)
• Monocotyledons (monocots)
This distinction is based primarily on the number of cotyledons, or seed leaves. In
addition, the two groups differ with respect to other anatomical features, such as the
arrangement of their vascular tissues, and their floral structure.
Review of plant anatomy
Leaves
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Vascular tissues
Cuticle
Mesophyll layer
Stomates and guard cells
Stems
• Vascular bundle
Roots
• Lateral roots
• Taproots
• Root hairs
Meristem
Localised developmental cells
– Apical meristems
1.Stem tips (longitudinal development-elongationup)
2.Root tips (longitudinal development-elongationdown)
3.Nodium (formation of branches)
– Lateral Meristem
1.Vascular cambium
2.Bark cambium
– Pericyle
(In root-inner meristematic layer)
Tissues in Plant
A) Dermal tissues;
– Epidermis
B) Ground tissue
– Paranchyma-photosyntesis
– Collenchyma-support-primary development-alive
– Sclerenchyma-support-secondary development-death
• Sclereids
• Fibers
C) Vascular tissues
– Ploem
– Xylem
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Cross section of root
Vascular bundle (Stele) = contains xylem and phloem
Cortex
Epidermis
Root hairs
– Absorb water and minerals
Stems
• support leaves to maximize light absorption
• part of conduit for transport of water, minerals, and
organic solutes
• storage
Cytokinesis in animal and plant cells
Fig. 7.1
Fig. 7.22
Plant vs. animal cells
• Plant
– Cell wall
– Plastids
– Tonoplast
• Animal
– No cell wall
– No plastids
– No tonoplast
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– Divide by inserting wall
– Plasmodesmata
– Ergastic deposits common
– Divide by pinching
– Gap junctions
– Deposits rare
– Modular construction
– Stem cells common
– Totipotent cells common
– Non-modular
– Stem cells rare
– No totipotency